Wire drawing machine



June 5, 1956 N- A. WILSON WIRE DRAWING MACHINE Filed Aug. 1, 1952 IN VENTOR.

NORMAN A. Wn so- ATTORNEY WIRE DRAWING MACHINE Norman A. Wilson,Westboro, Mass, assignor to Morgan Construction (Company, Worcester,Mass, 21 corporatron of Massachusetts Application August 1, 1952, SerialNo. 302,179

7 Claims. (Cl. 205-44) This invention relates generally to wire drawingmachines, and more particularly to wire drawing apparatus, in which thetensions in the wire are maintained at a desired value within very closelimits.

A continuous wire drawing machine may consist of a plurality ofrevolving blocks each connected to a common, driven jack-shaft by aclutch whose torque transmission characteristics may be changed asdesired. It is the usual practice to operate such a machine with theapplication of a fixed torque to each block, the value of the requiredtorque being determined by the particular drafting schedule, the size ofthe wire, desired back-pull, etc. For a particular drafting schedulewith a given wire size, the established back-pull at each die,determined by the torque transmitted to the preceding block, will remainconstant provided the wire characteristics at the position, such asdiameter and hardness, remain the same. However, the establishedback-pulls will increase or decrease with an increase or decrease of theinitial wire diameter, for instance. If the Wire variation is extreme,the back-pull may in crease to a value that will cause the wire to breakor, conversely, may decrease to a value that will develop slack wirewith subsequent wire breakage when the slack is suddenly taken up. Thepresent invention obviates these difficulties, as will be evident fromthe description which follows.

It is therefore an outstanding object of the present invention toprovide a wire drawing machine in which the torque delivered to theblocks is such as to maintain constant wire tensions throughout themachine.

A further object of this invention is the provision of apparatus forcontrolling the torque delivered to the first drawing block of a wiredrawing machine as a means of maintaining constant back-pull throughoutthe machine regardless of changes in qualities, such as diameter, of theentering wire.

Another object of the invention is the provision of an apparatus for usewith a hydraulic wire drawing machine for regulating the torquetransmission to the first block in response to the die reaction at thefirst die.

A still further object of the invention is the provision of apparatusfor maintaining within very close limits the torque transmission to ablock of a wire drawing machine at a value sufiicient, with theassistance of the back-pull on the following die, to overcome theresistance to drawing of the preceding die, but not enough to change theback-pull on the following die.

It is another object of this invention to provide a torque controlapparatus for wire drawing which contains no elements which are subjectto inertia, whereby it responds almost instantaneously to indications ofchange of wire quality.

Another object of this invention is the provision of apparatus of thetype described which is relatively inexpensive and which can be used inconjunction with existing machines.

With these and other objects in view, as will be apnited Patent parentto those skilled in the art, the invention resides in the combination ofparts set forth in the specification and covered by the claims appendedhereto.

The character of the invention, however, may be best understood byreference to certain of its structural forms, as illustrated by theaccompanying drawing, in which:

The single figure is a somewhat diagrammatic view of a wire drawingmachine embodying the present invention.

Referring to the drawing, a wire drawing machine, designated generallyby the reference numeral 10, com prises a first die box 11, a block 12,and a second die box 13. The first die box 11 is provided with a hingeddie holder 14, to which is fastened a die 15, through which a wire 16passes for the reduction thereof. Similarly, the die box 13 is providedwith a die holder 17 and a die 18. The block 12, which, in the preferredembodiment, is the first block in the machine, is generally cylindricaland is provided with a downwardly extending drive shaft 19 keyed to itsupper end to the block and at the lower end to a bevel gear 25 A mainmotor 21 is connected through a coupling 22 to a main jack-shaft 23,which extends the full length of the wire drawing machine and underliesthe blocks. The jackshaft passes through a hydraulic slip clutch 24 andis keyed to the input element thereof. The clutch 24 is of the typehaving input and output elements, the torque transmitted from the inputto the output element by the hydraulic fluid being proportional to thedifferential hydraulic pressure across the clutch. In other words, theclutch is a pump in which the output element is the reaction member andthe torque transmitted to the reaction member is in proportion to theresistance to flow of the fluid. Such a clutch is shown in the patent toMorgan No. 2,185,416 issued January 2, 1940. The output element of theclutch 24 is keyed to a bevel gear 25 which is coaxial with the mainjack-shaft and which is situated to mesh with the gear 2%. Hydraulicfluid, originating in a distributing pump, not shown, enters the clutch24 through an entrance conduit 26 and, after entering into the reactionbetween the input and output elements of the clutch, is dischargedthrough an exit conduit 27. The exit conduit is connected to the inletside of a pressure relief valve 28 which is provided with a motor 29which determines the setting of the valve. The valve 28 determines thepressure which is to build up on the exit side of the clutch 24 and,thus, determines the torque which will be transmitted through the clutchfrom the main jack-shaft to the block 12. The valve discharges through aconduit 30 to a reservoir, not shown. The motor 29 is geared to thevalve setting mechanism and, by actuating the motor, one is able to movethe valve mechanism in such a manner that the valve will open at aselected differential pressure. The differential pressure will be equalto the back pressure on the clutch 24-, less the inlet pressure, sincethe valve discharges to atmospheric pressure.

The die box 11 is provided with a back wall 31 through which passes anaperture 32 for the wire 16 and a threaded aperture 33 in the lowerportion thereof. A plug 34 is threaded in the aperture 33 and isprovided with a non-threaded, reduced portion 35 which protrudesinwardly of the box toward the lower portion of the die holder 14. Onthe surface of the reduced portion is fastened a strain gage 36. Thestrain gage is of the type containing an electrical resistance, thevalue of this resistance changing with the expansion and contraction ofan object to which the gage is attached. Such a gage is shown anddescribed in the patent to Simmons No. 2,292,549 issued February 23,1940. However, a strain gage may be used in which the electricalproperty which changes with strain is inductance or capacitance. Thegage is fastened to the cylindrical surface of the reduced portion 35 ofthe plug and is operative to indicate any change in length of theportion when it is subjected to axial stress. A keyway 37 is formed inthe side of the plug S-t and lead wires 33 and 35 from the gage areseated therein. The bottom of the lteyway is deeper than the root of thethread on the plug by an amount sufiicient for the lead wires to liebelow the crests of the threads in the aperture 33. The lead wires 3-3and 39 are, of course, electrically connected to the opposite ends ofthe resistance of the gage and their other ends are connected to theinput posts 4i) and re pcctively, of an analyzer 421 of a well-knowntype. The analyzer contains an element similar to an ohmrneter whichmeasures a resistance placed across the posts 40 and 41. This elementproduces a voltage signal proportional to the resistance and this signalis amplified by another element of the analyzer. The amplifier elementis selected for linear response, so that the signal appearing acrossoutput posts 51 and of the analyzer is proportional to the resistance ofthe strain gage 36.

A branch conduit 43 is attached to the entrance conduit 26 of the clutch24, while another branch conduit 44 is connected to the exit conduit 27.These conduits are connected to opposite sides of a differentialpressure gage 45. This gage is of a well-known type having an internaldiap iragm dividing the interior of the gage housing into two chambers.A resistance-type strain gage similar to the gage 36 is fastened to thesurface of the diaphragm to indicate deformation due to differentialpressure on opposite sides thereof. Thus, the gage 45 will indicate thedifferential pressure of the hydraulic fluid in the clutch 24 betweeninput and output, this iiiereutial pressure being proportional to thetorque transmitted by the clutch. Lead wires 46 and i7, originating onthe opposite ends of the resistance element of the gage 45, have theirother ends attached to the input posts 48 and 4-9 of an analyzer whichis similar in construction to the analyzer 42. The analyzers 42 and 5 3have the usual gain control for adjusting the degree to which theyamplify the signals originating in them, so that, irrespective of thevalue of voltages impressed on the input posts, the output signals ofthe amplifiers can be adjusted to be very nearly equal. The output post51 of the amplifier has a positive polarity, while the post 52 has anegative polarity; the output post 53 of the amplifier 5i has a negativepolarity; while the post 54 has a positive polarity. A common wire 55connects the posts of negative polarity 52 and 53. A voltmeter 56 isconnected by means of lead wires 57 and 53 to wires 59 and 6% which, inturn, are connected to the positive posts 51 and 54 of the amplifiers. Amain switch 61 is connected in series with the wire 59 adjacent thepoint of its connection with the lead wire 57.

Three power lines 62, 63 and 6- are connected at one end to the motor 29of the valve 23 and at the other end to a source of three-phase power,not shown. A founpolc, single-throw relay 65, having an actuating coil66, is connected to the power lines, so that one set of cont ctors 67 isinterposed in the line 62, while the other set of contactors 63 isinterposed in the line 63. The conta ors 67 and 6t: are normally open;that is to say, they errupt the lines in which they lie when no currentpasses through the coil 66. A jumper wire 69 connects the line 62 on thepower source side of the contactors to the line 63 on thc motor side ofthe contac- *s 6 A s r uniper wire 7t? connects the line on the powersource side of the contactors 68 to the line 62 on the motor side of thecontactors 67. A four-pole, single-throw relay 71, having an actuatingcoil 72, is connected to the jumper wires so that a set of contactors 73is interposed in the wire 70. The contactors 73 and 74 are normally openin that they do not allow current to pass through their respectivejumper wires when actuating current is not passing through the coil 72.The actuating coil 66 of the relay 65 is connected in series with acurrent rectifier 75 and a currentlimiting device 76. Thecurrent-limiting device 76 is of a well-known type having a set ofcontactors 77 and a coil 73 connected in parallel with the contactors,so that a small amount of the current passing through the device isshunted into the coil '78; when the total current passing through thedevice is such that a predetermined value is reached, the coil 78 opensthe contactors 77. The rectifier 75, the coil 66 and the device 76 areconnected across the wires 59 and 62 so that current may pass in onedirection only from the wire 59 to the wire 6t}, but, if the currentexceeds a pre etermined value for which the device 76 is the contactors77 will open, thus interrupting the How. A current rectifier 79, theactuating coil 72 and a current-limiting device 29 are connected inseries across the lines 59 and 60. The current-limiting device 8% isprovided with a set of contactors 3i. and an actuating coil 32 andoperates in a manner similar to the device 76. The rectifier 79 isconnected to permit the flow of current therethrongh in the directionopposite to that permitted by the rectifier 75, so that current willflow from the wire 60 to the wire 59, but only to an amount determinedby the device 80.

The operation of the invention will be evident in view of the abovediscussion. The wire 16 passes through the die 15 and the aperture andis wrapped around the block 12 from which it passes through the die 18.From there it continues through the Wire drawing machine in the usualmanner. With the machine operating at normal speed and with theback-pulls established in accordance with the size of the wire and otherfactors, the apparatus is balanced for this normal condition. This isdone by opening the switch 61 and adjusting the gain controls of theanalyzers 42 and to the point where the voltmeter 56 registers zero.When this is done, the voltage appearing across the posts 51 and 52, dueto the strain on the gage 36, is equal to the voltage appearing acrossthe posts 53 and 54 due to the strain on the gage 45. After theapparatus has been balanced in the manner described, the switch 61 isclosed. Any change in strain on the gage 36, due to increase in diereaction because of changes in wire size, etc., will cause acorresponding unbalance in the voltages on the outputs of the analyzers42 and 50. This unbalance will be indicated on the voltmeter 56. If thewire size increases, the die reaction on the first die 15 will increase.This will cause the die holder 14 to swing about its hinge so that thelower portion will press with greater force against the end of the plug34. The pressure of the die holder causes a compression of the reducedportion 35 only, since the remainder of the plug is threadedly held inthe aperture 33 in the back wall 31 of the die box 11. The compressionof the reduced portion of the plug is transmitted to the gage 36, sincethe two are firmly fastened together. The compression of the gage 36produces a change in its electrical resistance and the analyzerrecognizes this change by producing an increase in voltage across theoutput posts 51 and 52. This means that the original balance is upsetand a voltage difference exists between the wires 59 and 60.Consequently, current passes from the wire 59 to the Wire through therectifier 75, the coil 66 of the relay 65, and the current-limitingdevice 76. Passage of current through the coil 66 closes the normallyopen contacts 67 and 68, whereupon current passes through the powerlines 62, 63 and 64 to the motor 29. Actuation of the motor changes thesetting of the pressure relief valve 28, so that it produces a greaterback-pressure on the clutch 24. This causes the clutch to transmitgreater torque to the block 12. The net result is that the torquetransmitted to the block 12 is increased enough to compensate for theincrease in die reaction due to increase in wire size. When the motor 29has changed the valve 28 a certain amount, the differentialpressureacross the clutch 24 will be increased, this increasing thediiferential pres sure across the gage 45 and increasing its electricalresistance. The fact that the electrical resistance of the gage 45 hasincreased is noted by the analyzer 50, whereupon the voltage appearingacross the output posts 53 and 54 is increased. When this voltageincreases sufliciently to balance the voltage across the posts 51 and52, current will cease to flow through the coil 66 and the contacts 67and 68 of the relay 65 will open, thus stopping the transmission ofpower to the motor 29.

A decrease in die reaction due to a drop in wire size, for instance,Will cause the apparatus to function to reduce the torque transmitted tothe block 12. In this case, the current resulting from the unbalance ofthe system will flow from the wire 60 to the wire 59 through thecurrentlimiting device 80, the coil 72 of the relay 71 and the rectifier'79. The contactors 73 and 74 will close, causing current to passthrough the power lines to the motor 29, but with the opposite polarityso that the motor rotates in the opposite direction to that describedabove. Such a rotation of the motor reduces the pressure to which thepressure relief valve 28 is set, so that the back-pressure on the clutchis reduced and that torque transmitted to the block 12 is reduced. Thecurrent-limiting devices 76 and 8t prevent the apparatus from trying tocompensate for extraordinary changes in die reaction.

While certain novel features of the invention have been shown anddescribed and are pointed out in the annexed claims, it will beunderstood that various omissions, substitutions and changes in theforms and details of the device illustrated and in its operation may bemade by those skilled in the art without departing from the spirit ofthe invention.

The invention having been thus described, what is claimed as new anddesired to secure by Letters Patent is:

1. Apparatus for use with a wire drawing machine having a die and ablock, the said block being driven by a variable-torque actuating means,comprising means for obtaining a signal proportional to the torquetransmitted to the block by the actuating means, means for obtaining asignal proportional to die reaction, means for adjusting the torquetransmitted to the block by the actuating means, means for initiallybalancing the two signals, and means responsive to unbalance of thesignals to actuate the said adjusting means.

2. Apparatus for use with a wire drawing machine having a die and ablock, the said block being driven by a variable-torque actuating means,comprising means for obtaining an electrical signal proportional to diereaction, means for obtaining an electrical signal proportional to thetorque transmitted to the block by the actuating means, means foradjusting the torque transmitted to the block by the actuating means,means for initially balancing the two signals, means responsive tounbalance of the signals to actuate the said adjusting means.

3. Apparatus for use with a wire drawing machine having a die and ablock driven by a variable-torque clutch, comprising a first gageassociated with the die and having an electrical quality which changesin proportion to die reaction, a first analyzer connected to the gageand producing an electrical signal proportional to the said change inelectrical quality, a second gage associated with the clutch and havingan electrical quality which changes in proportion to the torquetransmitted by the clutch to the block, a second analyzer connected tothe gage and producing an electrical signal proportional to the saidchanges in electric quality of the second gage, means for balancing thetwo signals during normal, predetermined operation of the machine, anadjusting apparatus for changing the torque transmitted to the block bythe clutch, and means responsive to unbalance of the two signals toactuate the adjusting apparatus.

4. Apparatus for use with a wire drawing machine having a die and ablock driven by variable-torque means, comprising: a first gageassociated with the die and having an electrical property which varieswith die reactions, a first analyzer connected to the gage and measuringthe electrical property of the gage, a second gage associated with thevariable-torque means and having an electrical property which varieswith the torque transmitted to the block, a second analyzer connected tothe second gage and measuring the electrical property of the secondgage, means for comparing the measurements obtained by the analyzers,the variable-torque means being connected to the comparing means andresponsive to inequalities indicated thereby to change the torquetransmitted to the block.

' 5. Apparatus for use with a wire drawing machine having a die and ablock driven through a clutch, comprising: a first gage associated withthe die and having an electrical quality which varies with die reaction,a first analyzer connected to the gage and producing an electricalsignal proportional to the said electrical quality of the gage, a secondgage associated with the clutch and having an electrical quality whichvaries with the torque transmitted by the clutch to the block, a secondanalyzer connected to the second gage and producing an electrical signalproportional to the said electrical quality of the second gage, meansfor balancing the two signals during normal, predetermined operation ofthe machine, a motor-driven apparatus for adjusting the torquetransmitted to the block by the clutch, a relay responsive to unbalanceof the two signals to permit power to be transmitted to the motor foractuating the adjusting apparatus to compensate for said unbalance.

6. Apparatus for use with a wire drawing machine having: a die, a blockon which wire is Wound after leaving the said die, a hydraulic slipclutch connected to the block for transmitting power thereto, the torquetransmitted by the clutch being proportional to the pressure droptherethrough, comprising a relief valve for determining the pressuredrop in hydraulic fluid passing through the clutch, a motor foradjusting the relief valve, relays having coils and contactors throughwhich the said motor is connected to a source of power for the actuationthereof, a first strain gage connected to said die and having anelectrical property whose value is proportional to the die reaction, afirst analyzer connected to the first gage for measuring the value ofthe said electrical property and producing an electrical signal whosevalue is proportional to the said value of the electrical property, asecond gage associated with the clutch and having an electricalproperty, the value of which is proportional to the pressure dropthrough the clutch, a second analyzer connected to the second gage formeasuring the value of the said electrical property thereof andproducing an electrical signal whose value is proportional to the valueof the electrical property, means for equalizing the signals produced bythe analyzers during normal, predetermined operation of the machine, anexcess in value of one signal over the other causing current to flowthrough the coil of one of the relays for the actuation thereof.

7. Apparatus for use with a wire drawing machine having a die, a blockon which the wire is wound after leaving the said die, a hydraulic slipclutch connected to the block for transmitting power thereto, the torquetransmitted by the clutch being proportional to the pressure droptherethrough, and a relief valve for determining the pressure drop inhydraulic fluid passing through the clutch, comprising: a motor foradjusting the pressure at which the relief valve will pass fluid, afirst relay having a coil and contactors through which the said motor isconnected to a source of power for the actuation thereof in onedirection, a second relay having a coil and contactors through which thesaid motor is connected to the source of power for the actuation thereofin the other direction, a strain gage connected to said die and havingan electrical property which varies with the die reaction, a firstanalyzer connected to the strain gage for measuring the value of thesaid electrical prop erty and producing an electrical output signalwhose value is proportional to the value of the electrical property, adifferential-pressure gage connected across the clutch and having anelectrical property the value of which is proportional to the pressuredrop through the clutch, a second analyzer connected to thedifierentialpressure gage for measuring the value of the electricalproperty thereof and producing an electrical output signal whose valueis proportional to the value of the electrical property, means forequalizing the signals produced by the analyzers, the output signal ofeach analyzer appearing across two connecting posts, the posts of likepolarity being connected, the coil of the first relay being connected inseries With a rectifier across the other two posts, the coil of thesecond'relay being connected in series with another rectifier across theother two posts,

References Cited in the file of this patent UNITED STATES PATENTS2,205,213 Lessmann June 18, 1940 2,235,418 Buchhart Mar. 18, 19412,250,886 Blodgett July 29, 1941 2,263,246 Morgan Nov. 18, 19412,351,483 Carnagua June 13, 1944 2,449,608 Le May Sept. 21, 19482,588,834 Henderson Mar. 11, 1952 FOREIGN PATENTS 264,039 SwitzerlandDec. 16, 1949

